Base for electric lamps and similar devices



April 1, 1947.- E. B. ISAAC ETAL BASE FOR ELECTRIC 'LAMPS AND SIMILARDEVICES Filed May 6, 1943 2 Sheets- -Sheet l H 01: my w lnven't orsElmer" B. Isaac, Francis J. RippL,

Their- A't'tor'neg.

April 1, 1947- E. B. ISAAC ETAL 2,413,179

BASE FOR ELECTRIC LAMPS AND SIMILAR DEVICES 2 Shee ts-Sheet 2 mi e ai nap. T o J o 1TB .LL n .s k v m mmm Figs.

Patented Apr. 1, 1941 BASE FOR ELECTRIC LAMPS AND SIMILAR DEVICES ElmerB. Isaac, Cleveland Heights, and Francis J. Rippl, Cleveland, Ohio,assignors to General Electric Company, a corporation of New YorkApplication May 6, 1943, Serial No. 485,816

(or. ire-s2) 16 Claims.

presents novelty in methods of manufacture or as well as The fabricationand in apparatus therefor, novelty in base and envelope structures.

invention permits of simplifying and lowering the cost of the basestructure, of facilitating and lowering the cost of its manufacture andattachment, and of dispensing with soldering, welding, or other specialoperations in connecting the electrical device to the contact terminalmeans of the base.

In electric lamp manufacture, the general commercial practice is tofabricate as one unitary structure, separate from the lamp, a basecomprising an external metal shelP' provided with means for securing itin a socket, and also with one or more end contact terminals which areexposed at one end of the shell and are secured to the latter by a bodyof thermoplastic insulation (usually glass) molded or otherwise fastenedinto the shell. This separate, unitary base is subsequently mounted andcemented fast around the sealed neck end of a lamp envelope or bulb; andcurrent leads from the lamp bulb are connected to the contacts of thebase by soldering or welding. One type of base is known as a "bayonet"base because its metal shell is equipped with bayonet pins for securingit in a socket; another .is known as a "screw" base because its shell isscrew-threaded to screw into the socket. The screw shell customarilyserves as a contact terminal of the base; the bayonet shell" may or maynot be so used. Still other types of base are also employed.

In forms of our invention hereinafter described, we employ an externalbase shell or band for mechanically attaching the base directly to thelamp in such a way that the operation of attachment is also a principalstep in the fabrication of the base itself. In a screw or bayonet base,the shell may be screw-threaded or otherwise equipped for coaction witha. socket, and means of antiturning engagement between the lamp or bulband the base band or shell are provided, as well as means of shoulderedengagement for holding the parts together. Besides the insulator thatcarries one or more contact terminals. The preferred method offabrication and assembly is to cast the base band or shell around thebulb neck and the base insulator, and to embed any corresponding lamplead in the cast metal. We have also devised a way of casting the end orcenter contact terminal means into a base insulator and embedding thecorresponding lamp leads(s) in the casting(s)and this last method mayeven be employed in cases where the base shell does not in and of itselfsecure the base to the lamp bulb, but is cemented or otherwise attachedas heretofore known in the art. In general, however, there need be nooccasion for cementing, soldering, or welding to attach the base to thebulb or to connect its contact terminals to the lamp leads: on thecontrary, these operations may merge in the mere casting of the band orshell and the associated contact(s).

Various other features and advantages of the invention will becomeapparent from the description of species and forms of embodiment,

and from the drawings. The invention is herematter explained withparticular reference to bases of Edison and like screw and center or endcontact types; but it will be understood that it is also applicable tobases of other and very different types, such as the double end-contactbayonet type, for example.

In the drawings, Fig. l is a partial and mainly sectional side view of alamp based in accordance 'with the invention; Fig. 2 is a similar viewillustrating a. modified construction; Fig. 3 is a similar viewillustrating other modifications; and Fig. 4 is a perspective or tiltedend view of the base structure shown in Fig. 3, with a portion brokenout to show a radial section.

Fig. 5 is a partial sectional view of a lamp based according to theinvention in a modified form, with apparatus for. casting a part of thebase: and Fig. 6 is a perspective or tilted view of the base shown inFig. 5, with a portion of the lamp bulb.

Figs. '7 and 8 are partly sectional side views of a lamp based accordingto the invention as shown in Figs. 5 and 6, with apparatus for castinganother part of the base. I

Fig. 9 is a partial and mainly sectional side view of a lamp basedaccording to the invention, in a further modified form.-

Fig. 1 shows an incandescent lamp L whose bulb 20 has a reduced neckportion 2| terminating in an end seal 22 formed by interiusion withenvelope or bulb neck, these parts include a base the tubular stem flare23, through whose seal 3 press 24 the current leads 25. 26 enter thebulb. An exhaust tube 21 opens through the press 24 and is sealed oil atits outer end 23, beyond the neck end 22. Adjacent the neck end 22 is abase insulator 30 of hollow conical configuration, shown as engaging orabutting against a corresponding conical outer surface 3| of the bulbneck, and adapted to be made of glass or other heat-resistant insulativematerial. The insulator 30 has a central opening 32 for the lamp lead25, and a correspondingly apertured contact button 33 of ordinary sheetmetal rivet type may be molded or spun into the insulation around thishole 32 as usual. The lead wire 25 extends out through the opening 32and the contact 33, and is electrically connected to the latter bysolderlng or welding, as indicated at 34.

Around the peripheries of the neck end 2| and of the insulator 30 is athin metal band 35 which secures the parts together, being provided withshouldered engagement means for interlocking coaction with or behindcorresponding shouldered engagement means of the bulb neck and of theinsulator, and is shown as externally screwthreaded to serve as a screwcontact. As here shown, the bulb neck shoulder 36 is formed by one sideof an annular groove in the neck which accommodates a shoulder-forminginturned bevelled flange 31 at the upper edge of the band 35,?

while the outer margin or edge of the conical insulator 30 forms itsshoulder, and isrreduced on a corresponding bevel at 38 to accommodate ashouldered inturned bevelled fiange 39 at the lower edge of the band 35.Any suitable means of antiturning engagement may be provided on the bulbneck 2| and on the band 35, such as external depressions 40 in the bulbneck into which look corresponding internal teeth on the band, or viceversa. As shown, the lamp lead 25 extends out between the conical bulbneck surface 3| and the corresponding internal surface of the insulator,either of which may be grooved to accommodate this wire, and its outerportion is electrically connected to the band or shell 35. As explainedhereinafter, the band 35 may be die-cast around the parts 2|, 30 in therelations thereto above described, and the outer portion of the leadwire 26 may be embedded in the fused metal of the band when itsolidifies, and thus connected thereto.

The construction illustrated in Fig. 2 is like that of Fig. 1 exceptthat the end contact button 33a is cast into the lead hole 32 of theinsulator 30a, whose end is reduced on a bevel at 4| to accommodate abevelled annular flange on the button.

Fig. 3 shows a construction very similar to that in Figs. 1 and 2, butwith a base insulator 30b having a wide-angled internal conical surfacethat abuts and fits snug against the usual rounded neck end adjacent itsperiphery at 3|. Also, the insulator shoulder 38b is formed b P ripheralreduction of the insulator, and the corresponding interlocking portionof the band 35 is a mere internal shoulder. The end contact button 33bis shown as cast into the lead hole 32 and around a shoulderedprotuberance 'ilb on the end of the insulator, and the lead hole 32 isconsiderably enlarged at 32.1: to allow for a head 331: east integralwith the button 33b. The lead 25 is embedded in the cast metal of theseparts 33b, 33a.

Fig. 4 illustrates another modified form of base insulator 30c.specially suitable to be made of transparent material, like glass. Itdifiers in having an unreduced periphery, with a shoulder 380 formed bythe flat top surfacepf its margin. As shown,-there is a radial groove 43in the end of the central head Me to accommodate the outward bent lead25, and there is a similar groove 44 across the periphery of theinsulator'30c to accommodate the lead 26. As shown in Fig. 4. lettersand figures indicating the voltage, and wattage, etc., of the lamp orother device may be marked on the inside surface cf'the insulator 300 soas to be read easily through it, while at the same time protected fromdefacement.

Fig. 5 illustrates the basing of a lamp and the concomitant casting of aband 35d according to the invention, certain modifications of the bulbneck and of the base insulator being also shown. At the left of Fig. 5,the mold cavity D for the band 35d is shown empty, while at the right itis shown filled with the cast metal. As regards the base insulator 30d,the modifications consist mainly in a rounded, dome-like configuration,in a high central protuberance or boss 4|d peripherally reducedto take amarginal flange of the cast-on button 33d and in an internal bevel 3|dat the upper edge of the insulator, with radial grooves 4411 toaccommodate the lamp lead 25. As regards the bulb neck 2|d, themodification consists in a simpler configuration than in Figs. 1, 2, and3. Fig. 6 shows the base as produced and attached according to Fig. 5,and shows letters and figures marked on the inside surface of atransparent insulator 30d, where they are protected from defacement, toindicate the voltage, and wattage of the lamp, etc. The convexconfiguration of the insulator 3011 results in apparent magnification ofthese letters and figures. Other letters indicative of the make of thelamp (or the like) are shown as cast into the center contact button 33d.

Fig. 5 illustrates the basing of a lamp according to the invention bydie-casting a band 35d around the base insulator and the bulb neck.Thegeneral technique illustrated is of course applicable to other formsof construction besides that shown in Fig. 5. The center contact button33d shown in Fig. 5 may be cast on to the insulator 30d as a separateoperation, either before or after casting the band 35d.

For casting the band 35d, Fig. 5 shows a mold 50 associated with andsurrounding the base insulator 30d and the bulb neck 2| d. This mold 50,which may be of iron or mild steelor other suitable metal, has a centralend opening 5|, here shown at its bottom, and comprises a plurality ofannular sections. These may consist of a lower part 52 having upper andlower internal annular shoulders 53, 54 to seat and center the insulator30d, and an upper part 55 seated and centered around a reduced externalannular shoulder 56 on the part 52 and extending up around the upperportion of the insulator 30d and around the bulb neck 2| d. To form theband 35d, the mold 50 affords a radially thin annular mold cavity Doverlapping behind or above the shouldered dowelbosses 35d of the neck2|d and also behind or below the rounded shoulder 33d of the domeshapedinsulator 30d. As shown, this mold cavity D lies mainly or entirely inthe upper mold section 55. To form external screw threads on the band35d, there is a rounded helical groove 51 in the internal surface of themold section 55. For the passage of molten metal from the bottom opening5 where it is introduced, up into the annular cavity D, there andupward-sloping channels or grooves 53 are numerous outward across theannular shoulders ll, on which the base insulator 80d rests, giving thisportion of the mold wall a fluted character, so that the molten metalcan travel upward outside the in sulator, and even without coming incontact with it at all.. The molten metal may be introduced into theopening 5| by any suitable means, here indicated as upward-open conduitor spout 59 through which the metal may flow under suitable pressure.

When the apparatus is to be used, the mold 50 is heated by any suitablemeans (not shown) hot enough to obviate rapid chilling andsolidification of molten metal as it strikes the mold wall. The

insulator 30d and the bulb d having been placed in the mold as shown,with the lead wire 28 extending out and up into the mold cavity D, andthe lead extending down into the opening 32d, the parts are rapidlyrevolved together about an upright axis coincident with their own axes,and a sufficient charge of molten metal is forced through the conduit 59and discharges therefrom into the moldlopening 5|, amongst the metalridges or flutes" 'which define and separate the grooves 58. With themold 50 revolving at adequate speed, the centrifugal force lifts themetal along the sloping grooves 58 and distributes it unformlythroughout the mold cavity D, completely filling the latter to form theband d, and securing the parts 20d and 30d together... As soon as themetal cools and solidifies in the mold which may be hastened by blowingjets of air or other cooling fluid.(not shown) against the exterior ofthe mold-the completed assembly of parts can be removed and replacedwith another insulator 30d and bulb 20d, and the casting operation canbe repeated.

As illustrated in Figs. 7 and 8, the casting of the contact button 33dmay be done in a separate stationary open-top mold 60 into which moltenmetal is introduced under pressure through 9. lateral conduit or spout6| delivering into said mold when the latter is lowered away from theinsulator 30d as shown in Fig. '1. The mold 80 is then raised againstand around the insulator boss Md, so that the molten metal in the moldrises into the insulator lead hole 32d and its enlargement 323:, Fig. 5.During these operations, the lamp L may be held as shown, with thereduced lower portion of its insulator 30d engaged in a bevelled openingin a supporter 62, .and with an aligning cup-like top holder 63 bearingon the upper end of the bulb 2Id. Thus an enlarged head is formed in theinsulator 30:1 to secure the button 33d to the latter, and the outerportion of the lead wire 25 is embedded in this head and in the button.The mold 80 fits and seals around the conical insulator 30d when themold comes up against the insulator. The mold 60 may in use be heatedsuiliciently to avoid premature solidification of the molten metal.

Any metal (or alloy) suitable for die-casting can be used to cast theparts 33d. 35d as above described, provided its melting point is not sohigh as to soften or injure the materials of the bulb neck Md and of theinsulator. Type metal is very suitable for use with the ordinary softglass of incandescent lamp bulbs.

Fig. 9'lllustrates a modification in which the base is applied to askirt extension 2la: of the bulb neck 2| that projects beyond the stemflare or mount seal 22, this seal being a substantial distance behindthe extreme end of the neck or skirt. Thus it is the skirt 2k: thatcarries the shouldered bosses or dowels llefwhich are shown solid.rather than as hollow embossments as in Fig. 5. The lower inner cornerof the skirt 2k: is shown rounded away at 3 la, and the upper edge ofthe dome-like base insulator tile is bevelled outward at 38c, instead ofinward as in Fig. 5. The material to form the skirt 2lx may be providedin sealing the mount into the bulb, by retaining a short cullet" portionof the bulb neck integral with the seal at 22, instead of fusing it of!as usual.

In Figs. 2-9, various parts and features are marked with the samereference characters as are applied to corresponding ones in Fig. 1, inorder to dispense with repetitive description-a distinctive letter beingadded where such distinction appears necessary.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

l. The combination with an electric lamp having a bulb with ahermetically sealed and externally shouldered neck end presentingantiturning engagement means, and a shouldered base insulator at saidneck end of said bulb carrying a center contact button, of a cast metalscrew shell contact around theperipheries of said neck end and saidinsulator interlocked behind their shoulders, whereby said parts aresecured to one another, and also antiturningly engaged with saidantiturning engagement means of said neck end, a lamp lead extending outthrough said centercontact button and electrically connected thereto,and a lamp lead extending out between said neck end and said baseinsulator to said screw shell, and electrically connected to the latter.

2. The combination with a bulb having a neck with dowel meansdistributed therearound, and a base insulator also having shoulderedengagement means therearound and carrying center contact means, of acast metal screw shell contact around said neck and said base insulatorand interlocked with their dowel and engagement means aforesaid, wherebysaid parts are secured together and turning'of said screw shell relativeto said bulb is prevented.

3. The combination of an electricjamp having a bulb with a shoulderedneck, a shouldered base insulator at the neck end of said bulb having anend-contact lead opening, with leads from said lamp severally extendingout through said endcontact lead opening and out between said bulb neckand said base insulator, and a cast metal contact band around said neckand said base insulator and locked behind their shoulders, and having anouter portion of the last-mentioned lamp lead embedded therein.

4. The combination of an electric lamp having a bulb with a hermeticallysealed and externally shouldered neck and presenting antiturningengagement means, a shouldered base insulator abutting against said neckend and having an end-contact lead opening, with leads from said lampseverally extending out through said endcontact lead opening and outbetween said bulb neck end and said base insulator, and a cast metalscrew shell contact around said neck and said base insulator and lockedbehind their shoulders and with said antiturning engagement means, andhaving an outer portion of the last-men-l tioned lamp lead embeddedtherein.

5. The combination of an electric lamp having a bulb with a shoulderedneck, a shouldered base insulator at the neck end of said bulb having anend-contact opening, with leads from said lamp severally extending outthrough said opening and out between said neck and said base insulator,a cast metal contact band around said neck and base insulator and lockedbehind their shoulders, with an outer portion of the last-mentioned lamplead embedded therein, and a cast metal endcontact in the aforesaidopening of said insulator, with an outer portion of the first-mentionedlead embedded therein.

6. The combination of an electric lamp having a bulb with a neck havingdowel means distributed therearound, and a base insulator at the neckend of said bulb having an end-contact opening and also havingshouldered engagement means therearound, with leads from said lampseverally extending out through said opening and out between said neckand said base insulator, a cast metal screw shell contact around saidneck and said base insulator and interlocked with their dowel andengagement means aforesaid, with an outer portion of the last-mentionedlamp lead embedded therein, and a cast metal end-contact in theaforesaid opening of said insulator, with an outer portion of thefirst-mentioned lead embedded therein.

7. A method of basing a lamp having a shouldered neck which comprisesplacing the lamp and a shouldered base insulator at the end of said neckin a mold surrounding said parts with an annular mold cavity overlappingbehind their shoulders, and introducing molten metal into said annularmold cavity to fill the same while rotating said mold, lamp, and baseinsulator at sufficient speed to centrifugally distribute the moltenmetal throughout said cavity, continuing rotation of the parts until themetal solidifies.

8. A method of basing a lamp having a shouldered neck which comprisesplacingthe lamp and a shouldered base insulator at the end of said neckin a mold surrounding said parts with an annular mold cavity overlappingbehind their shoulders and having a central opening at the end of theinsulator, with passage therefrom outward to said annular mold cavity,and introducing molten metal into said opening to fill said cavity whilerotating said mold, lamp, and base insulator at sufflcient speed tocentrifugally distribute the molten aforesaid and throughout saidcavity, continuing rotation of the parts until the metal solidifies.

9. A method of basing a lamp having a shoul- I dered neck whichcomprises placing the lamp and a shouldered base insulator at the end ofsaid neck upright in an upwardopen mold seating and sustaining saidinsulator below its shoulder and surrounding adjacent portions of thesaid lamp neck and insulator with an annular mold cavity overlappingabove and below their respective shoulders, and also having a centralopening be neath said insulator with passage therefrom upward andoutward to said and introducing molten metal into said opening to fillsaid cavity while rotating said mold, lamp, and base insulator atsufficient speed to centrifugally distribute the molten metal throughthe passage aforesaid and througout said cavity, continuing rotation ofthe parts until the metal solidifies.

10. Apparatus for basing a lamp having a shouldered neck with ashouldered base insulator at the end of said neck, said apparatuscomprising a mold for surrounding adjacent portions of said neck andinsulator with an annular mold cavity at its upper end overlappingbehind the" shoulders of said lamp-neck and insulator and annular moldcavity,

lamp, and base metal through the passage l shoulder, and also having acentral opening at its lower end opposite the end of the insulator, withpassages inclined outwardly and upwardly therefrom to said annular moldcavity, means for introducing molten metal into said opening to fillsaid cavity, and means for rotating said mold,

about their vertical axes to centrifugally pass the molten metal upwardthrough said passages and distribute the same throughout said cavity.

11. In an electrical device of the class described comprising a sealedglass bulb havin a neck portion, a base comprising an insulator bodycovering and engaging the end of said bulb neck and secured thereto by acast metal shell circumposed directly on and spanning adjacent portionsof said bulb neck and insulator body, said metal shell being cast inplace around said bulb neck and insulator and being shaped to engage ina socket.

12. In an electrical device of comprising a sealed tion with lead wiresextending therefrom, a base comprising an insulator body carryin acontact member and covering and engaging the end of said bulb neck andsecured thereto by a cast metal shell circumposed directly on andspanning adjacent portions of said bulb neck and insulator body, saidmetal shell being cast in place around said bulb neck and insulator andbeing shaped to engage in a socket, one of tending to and beingelectrically connected with said shell, and another lead wire extendingto and being electrically connected with said contact member on saidinsulator body.

13. In an electrical device of the class described comprising a sealedglass bulb having a neck portion, a base comprising an insulator bodycovering and engaging the end of said bulb neck and secured thereto by acast metal shell circumposed directly on and spanning adjacent portionsof said bulb neck and insulator body, said metal shell being cast inplace around said bulb neck the class described and insulator and beingshaped to engage in a shell circumposed directly on and spanningadjacent portions of said bulb neck and insulator body, said metal shellbeing cast in place around said bulb neck and insulator and being shapedto engage in a socket, the portions of said bulb neck and insulator bodycircumposed by said shell being configurated to provide interlockingengagement of the shell therewith against separation or rotation of saidinsulator body relative to said bulb neck, one of said lead wiresextending to and being electrically connected with said shell, andanother lead wire extending to and being electrically connected withsaid contact member on said insulator body. 7

15. In an electrical device of theclass described comprising a sealedglass bulb having a neck portion with lead wires extending therefrom. abase comprising an insulator body carrying a contact glass bulb having aneck porsaid lead wires examam member and covering and engaging the endof said bulb neck and secured thereto by a cast metal shell circumposeddirectly on and spanning adjacent portions of said bulb neck andinsulator body, said metal shell being cast in place around said bulbneck and insulator and bein shaped to engage in a socket, one of saidlead wires extending to and being embedded at its end in said shell, andanother lead wire extending to and being electrically connected withsaid contact member on said insulator body.

16. The method of basing a glass electric lamp bulb having a neckportion which comprises placing a base insulator against said neckportion, surrounding said neck portion and insulator with a mold havinga cavity overlapping adjacent portions of said neck portion andinsulator, introducing molten metal into said cavity to fill it whilerotating said mold, bulb and insulator at sufllcient speed tocentrifugally distribute the molten metal throughout said cavity, andcontinuing rotation of said parts until the metal solidifies.

ELMER B. ISAAC. FRANCIS J. RIPPL.

RWERENCES CITE UNITED STATES PATENTS Number Name Date 2,257,475 MetzSept. 30, 1941 2,256,062 Taylor Sept. 16, 1941 2,290,073 Said July 14,1942 645,266 Kremenezky Mar, 13, 1900 653,038 Piechati July 3, 19001,806,787 Conradty May 26, 1931 2,275,503 Brown Mar. 10, 1942 2,149,702Maris Mar. 7, 1939 1,650,289 McGinley Nov. 22, 1927 1,556,342 Peth Oct.6, 1925 2,159,812 Malloy May 23, 1939 1,965,231 Gustin July 3, 1934

